1. Technical Field
System and method for displaying power flow in a hybrid vehicle.
2. Background Art
Conventional vehicles, such as those powered by a single internal combustion engine, often provide a vehicle operator with information through a number of commonly used displays. For example, speedometers, odometers, tachometers, fuel level gauges, oil level indicators and engine temperature gauges are commonly used to provide information in analog and/or digital form. With the increase in prevalence of non-conventional vehicles, such as hybrid vehicles, a need has arisen to provide a vehicle operator with additional information unique to these non-conventional vehicles.
The parallel-series hybrid electric vehicle (PSHEV) has powertrain characteristics of both a parallel hybrid electrical vehicle and a series hybrid electric vehicle (SHEV). The PSHEV includes an engine, an electric generator, and an electric motor. Both the engine and the electric motor can be coupled to the drive wheels of the vehicle to provide propulsion power to drive wheels of the vehicle. In addition, the generator and the motor can be referred to as electric machines since either is capable of acting as a motor under certain driving conditions and as a generator under other driving conditions.
The PSHEV powertrain is sometimes known as a “power-split” hybrid vehicle because the engine power output is “split” by a planetary gear set between a series path from the engine to the electric generator and a parallel path from the engine to the drive wheels.
The PSHEV has two power sources. The first power source of the PSHEV includes the engine and the electric generator, including a power transfer unit, such as a planetary gear set. The power transfer unit mechanically couples the engine, the drive wheels, and the electric generator. The electric generator of the PSHEV is usually connected to the sun gear of the planetary gear set. The engine is usually connected to the planetary carrier while the drive wheels are usually connected to the ring gear. In a negative split mode, the generator in the PSHEV outputs power to the planetary gear set. In a positive split mode, the generator receives power from the engine through the planetary gear set. The negative and positive split modes may be referred to as power operation modes of the PSHEV.
The second power source of the PSHEV is an electric drive including the electric motor, the electric generator, and an energy storage device (hereinafter “battery”). The battery in the PSHEV is electrically coupled to the electric traction motor as well as the electric generator. The battery can act as an energy storage medium for both the electric generator and the electric motor. In operation, the electric generator can provide electric power to either the battery, the electric motor, or both the battery and the electric motor. The electric motor, the electric generator, and the battery may be referred to as an electric drive system.
Since the PSHEV has both the engine and the electric motor, the PSHEV can be powered by either one or both of these torque-producing devices. Thus, the PSHEV can selectively use the engine, the electric motor, or both in combination to provide propulsion power to the drive wheels.
In these types of vehicles, it may be beneficial to provide a vehicle operator with information regarding the flow of power between these various devices, and to and from the drive wheels. Such information may be important to the operation of the vehicle. In addition, such information may provide a vehicle operator with a better understanding of the operation of the non-conventional vehicle.
An information display for a hybrid vehicle is described in a U.S. Patent Application having Publication Number 2007/0208468 and a publication date of Sep. 6, 2007.